How to transform a union of objects to a plain union with object's values. An example:
type Foo = {};
type Bar = {};
type Baz = {};
type Qux = {};
type Input = {
foo: Foo,
bar: Bar,
} | {
bar: Bar,
baz: Baz,
} | {
qux: Qux,
};
type Expected = Foo | Bar | Baz | Qux;
Pay attention that keys of union's objects may intersect (bar in example). Hope the solution advance me unwrapping nested typings.
You want to take something like a ValueOf<T> type (which is just T[keyof T]) and distribute it across the union members of T so that if T is, for example, A | B | C, then Transform<T> is A[keyof A] | B[keyof B] | C[keyof C]. You can use a distributive conditional type to get that behavior:
type Transform<T> = T extends any ? T[keyof T] : never;
Let's test it:
type Output = Transform<Input>
// type Output = Foo | Bar | Baz | Qux
Looks good.
